Jamming device for rope and alike

ABSTRACT

Jamming devices for rope comprise a casing (2) consisting of two pallely, one above the other situated flanges (3, 4) between which are perpendicularly mounted the first and the second pulleys (12, 13) as well as a jamming cleat (14). The second pivoting pulley (13) is fastened to the lever (11); the latter is pivoted eccentrically to centre of the pivoting pulley (13) and can be swayed to and fro within the limits determined by the design. The second pivoting pulley (13) is in functional relationship with the fixed pulley (15) and so the rope (10) can be wedged between the fixed pulley (15) and the second pivoting pulley (13) in the first jamming position. The lever (11) can be by means of the arc-adjuster (16) moved away from the fixed pulley (15). In functional relationship with the jamming cleat (14) is the press-boss (17); between the latter and the jamming cleat (14) the rope (10) can be wedged in the second jamming position. Thereby is warranted that the user, who hangs on the rope (10) threaded through the jamming device (1), can safely descend and/or ascend along the rope.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention concerns a jamming device for rope and alike whose casingconsists of two parallelly, one above the other, situated flanges.Between the said flanges are perpendicularly mounted two pivotingpulleys and a jamming cleat.

A similar jamming device, used chiefly in alpinism for ascending anddescending along the rope, is known under FR-PS 2,451,752. On at leastone of its flanges are mounted a first and a second pivoting pulleys, bymeans of which occurs during ascending and/or descending a relativemotion between the rope and the said pulleys.

Fastened to the casing is also a fixed pulley along which is wound therope. To effect a jamming position between the fixed pulley and thefirst pivoting pulley is the fixed pulley in functional relationshipwith the first pivoting pulley. The latter, however, is coupled with theoperating handle which is pivotally mounted between the two flanges. Thefirst pivoting pulley is additionally equipped with two bosses facingthe fixed pulley. These bosses wedge, in association with the fixedpulley, the rope in two jamming positions.

To make threading of the rope into the jamming device easier is one ofthe flanges retractable, thus allowing the rope to be wound around thepivoting pulleys and in particular between the first pivoting pulley andthe fixed pulley.

If the user wishes to descend he embraces the handle with hand andpushes it in the middle position. A relative motion between the rope andthe individual components of the jamming device ensues when neither ofthe first pivoting pulley's bosses blocks the rope between the saidbosses and the fixed pulley--that is to say, when the rope is allowed toslide smoothly between the first fixed pulley and the first pivotingpulley. The first jamming position is activated by pressing the handleagainst the casing. Thus the user causes the first boss of the firstpivoting pulley to edge the rope between the first pivoting pulley andthe fixed pulley.

The second jamming position is activated by pushing the handle away fromthe casing until the angle of about 90° has been reached; then the ropeis wedged between the second boss of the first pivoting pulley and thefixed pulley.

If the user releases the operating handle he causes the first pivotingpulley to rotate anti-clockwise until the operating handle gets pressedclosely against the casing. The weight of user's body namely effects inthe first pivoting pulley a moment of anti-lockwise rotation, activatingso automatically the first jamming position of the rope.

A drawback of the jamming device under consideration is the occurrencethat the first jamming position of the rope gets activated only when theoperating handle is pressed firmly against the casing. Therefore theuser is forced to remove the fingers he has between the handle and thecasing, and then press with hand the handle against the casing if hewishes to wedge the rope safely in the first jamming position. If ithappens--say, in the case of accident--that the user is unable to pressthe handle against the casing, the moment of rotation generated in thefirst pivoting pulley will activate the first jamming position in whichthe rope is wedged between the first boss and the fixed pulley. However,the weak point of this first jamming position is that it does not wedgethe rope safely, for the jamming force generated by the first boss andthe fixed pulley depends on the moment of rotation created in the firstpivoting pulley as well as on the magnitude of force of friction betweenthe rope, the fixed pulley and the boss. If the jamming force is smallerthan the force of friction the jamming device does not hold the userfirmly in place, and thus he slides downwards. This happens particularlyif the rope's diameter is too small and/or the rope's surface is toosmooth.

As to the second jamming position, its disadvantage is that the requiredangle between the handle and the casing is about 90°. This implies thatgreat physical strength is required from the user not only to activatethe second jamming position but also to retain it, for he has tooverpower all the time the moment of rotation generated by the weight ofuser's body in the first pivoting pulley.

The said large opening angle of 90° has for the user another adverseconsequence: the contact of user's hand with the casing gets lostimmediately after the opening angle of the handle has reached thedistance exceeding the span of his hand.

BRIEF SUMMARY OF THE INVENTION

The purpose of invention is to produce a jamming device that will offersafe descending and/or ascending along the rope threaded through thejamming device, provide fast and easy inserting of the rope, and requirea small opening angle between the handle and the casing. Accordingly,the user's hand will remain in permanent contact with the handle and thecasing--which means that the user will not be forced to remove his handwhen operating the device.

Further shall the jamming device provide at least one jamming positionin which the rope will be--regardless of the user's condition, that isto say, even if he has fainted away--automatically wedged safely. Thusin the case of a fall the user will not be in danger to slide downwardsalong the rope wound through the device; moreover, the thickness andproperties of the rope's surface will have no impact on effectiveness ofthe jamming position.

The purpose of the invention has been achieved in the following way:

The second pivoting pulley is fastened to a lever that is pivotedeccentrically to the centre of the first pivoting pulley; around thesaid pivot the lever can be swayed to and fro.

Associated with the second pivoting pulley is a fixed pulley; betweenthe latter and the second pivoting pulley is the rope wedged in thefirst jamming position.

The lever can be by means of an arc-shaped adjuster moved away from thefixed pulley.

Associated with the jamming cleat is a press-boss; between the latterand the jamming cleat is the rope wedged in the second jamming position.

Notably, the lever is pivoted eccentrically to the geometrical axis ofrotation of the first pivoting pulley whereby is in each position of thelever provided a lever-arm. Thus is the lever, owing to the weight ofuser's body, continuously driven towards the casing, irrespective of therope's diameter and properties of the rope's surface.

The first pivoting pulley and the lever are coupled together, which isanother distinguished feature of the jamming device for it simplifiesits design. Fastening of the jamming cleat to the lever affords safewinding of the rope as well as a large jamming surface and therefore nomajor effort is required to wedge the rope safely between the jammingcleat and the press-boss. A prominent feature of the design is also thatthe angle between the handle and the casing cannot exceed 60° and thusthe user's hand can remain in permanent contact with the handle and thecasing respectively.

The centre of the second pivoting pulley is in vertical direction alittle removed from the lever's axle which distance depends onpositioning of the lever's axle as determined via design. Therefore apredetermined moment of rotation urges the second pivoting pulley tomove towards the fixed pulley, which implies that for activating thesecond jamming position but a minor physical effort is required from theuser. On the other hand, the first jamming position gets activatedautomatically, without application of any force; a minor physical effortis required merely to disengage the first jamming position. Moreover,the first jamming position offers to the user a high degree of safetyfor it gets activated automatically as soon as the user releases thehandle--say, in the case of an accident.

Through the lever is established a mutual relationship between bothpivoting pulleys and the jamming cleat, which is another characteristicfeature of the design. However, it is also possible to separate thefirst pivoting pulley from the lever. Further, it is possible to locatethe lever without the casing unless the lever's freedom is impeded byone of the flanges.

Additional distinguished design features of the invention are evidentfrom the claims which follow.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

An example of jamming device conformable to the invention is shownsubsequently by means of drawings. The individual drawings show:

FIG. 1: Elevation view of the jamming device with a flange on which aremounted two pivoting pulleys. They are mutually connected via a lever towhich is fastened a jamming cleat. On the said flange is mounted also afixed pulley to which is pivotally attached the operation handleequipped with an arc-shaped adjuster and a press-boss.

FIG. 2: Jamming device as in FIG. 1; shown is the first possibility ofinserting the rope.

FIG. 3: Jamming device as in FIG. 1; shown is the second possibility ofinserting the rope.

FIG. 4: Jamming device as in FIG. 1; shown is the first jamming positionof the rope.

FIG. 5: Jamming device as in FIG. 1; shown is the second jammingposition of the rope.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the jamming device 1, comprising the casing 2 whichconsists of two flanges 3 and 4; flange 4 is not shown in the drawing.

Flanges 3 and 4 are fastened together with bolts 5 and 6, whereby isfixed the distance, determined via design, between the flanges 3 and 4.Bolt 5 serves also as axle 21 of the lever 11. In the shown example ofthe device are to the lever 11 fastened two pivoting pulleys 12, 13 andthe jamming cleat 14.

The second pivoting pulley 13 has the shape of a droplet whose pointfaces the jamming cleat 14. One flank of the pivoting pulley 13 isturned towards the fixed pulley 15, which is via bolt 6 mounted betweenflanges 3 and 4.

The jamming cleat 14 is kidney-shaped, which gives it within its reachthe maximal surface matching the rope 10. The fixed pulley 15 has acircular form.

The lever 11 can be by means of the arc-shaped adjuster 16 pushed out ofthe casing 2. Under the arc-shaped adjuster 16, at the side turned awayfrom the fixed pulley 15, is situated a press-boss 17. To make handlingeasier are the arc-shaped adjuster 16 and the press-boss 17 extended bythe handle 18.

Partial cross-section of the fixed pulley 15 in FIG. 1 shows thearc-shaped adjuster 16 which is equipped with a rotation stop 19. Thelatter restrains the movement of the arc-shaped adjuster 16, press-boss17 and handle 18. In view of that is magnitude of the angle α betweenthe handle 18 and the casing 2 limited to about 60°. This angle matches,by and large, the normal size of human hand and so even at maximalmagnitude of the angle α four fingers of user's hand remain in contactwith the casing 2, while the thumb remains in contact with the handle18. Accordingly, if necessary, the user can press the handle 18 againstthe casing 2.

Either of the two flanges 3 and 4 has at the end turned away from thefixed pulley 15 an oblong hole 8 into which a carabiner 9 is fitted. Thelatter links, via rope which is not shown in the drawing, the user withthe jamming device 1. Consequently, the jamming device 1 is permanentlyunder the weight of user's body.

The way of handling the jamming device 1 is shown in FIGS. 2 to 5.Identical components of the device are consistently marked with the samenumbers as in FIG. 1.

FIG. 2 shows the first possibility of inserting the rope 10. Tofacilitate this operation the user ought to sway the lever 11 out of thecasing 2. Then winding of the rope 10 around the pivoting pulleys 12 and13 is carried out easily and fast.

FIG. 3 shows the second possibility of inserting the rope 10. In thiscase the latter is threaded into the casing 2 under the fixed pulley 15.This alternative permits use of a thicker and less flexible rope 10which is of consequence in the case the user does not possess a suitablerope 10 that could be threaded into the jamming device 1 as shown inFIG. 1.

Both alternatives of inserting the rope 10 have a common characteristic:in either case is the rope 10 wound almost entirely around thedroplet-shaped pivoting pulley 13. Owing to its specific shape thepivoting pulley 13 offers, in association with the fixed pulley 15, sucha large matching surface for the rope 10 that its thickness andproperties of its surface have little impact, if any, on the respectivejamming position.

The first jamming position, where the rope 10 is wedged between thepivoting pulley 13 and the fixed pulley 15, is shown in FIG. 4. Thisfirst jamming position is activated automatically by the lever 11through the force generated in rope 10 by the weight of user's body,which force moves the lever 11 towards the fixed pulley 15.

In FIG. 4 is this jamming position shown schematically by the help ofarrows marked with N. These arrows N correspond to the normal forceacting upon the rope 10 in this jamming position.

Movement of the lever 11, and simultaneously of the pivoting pulley 13,is brought about by the moment of rotation generated around the axle 21of the lever 11. The said moment equals the product of the weight ofuser's body and the lever-arm a. The latter is the rectangular distancefrom the line of action of the force generated in rope 10 to the axle 21of the lever 11. This moment of rotation is affected by another momentof rotation which also acts around the axle 21 of the lever 11. Thissecond moment of rotation equals the product of force of friction,generated through joint action of the rope 10 with the pivoting pulley12, and the lever-arm b. The lever-arm b corresponds to the radius atwhich the rope 10 encircles the axle 21 of the lever 11.

To ensure that in each position of the lever 11 a sufficient moment ofrotation urges the lever 11 to move towards the fixed pulley15--regardless of the weight of user's body, diameter of the rope andproperties of rope's surface--is the axle 21 of the lever 11 positionedeccentrically to the geometrical axis of rotation of the pivoting pulley12.

The arc-shaped adjuster 16 works in this first jamming position inassociation with the lever 11; thus by pushing the arc-shaped adjuster16 towards the fixed pulley 15 the user moves the lever 11 away from thefixed pulley 15. In view of that the distance between the fixed pulley15 and the pivoting pulley 13 increases until the jamming position isreleased and the rope 10 set free.

Motion of the lever 11 can be controlled by means of the convex curveincorporated in the arc-shaped adjuster 16 and so the user is able toincrease the cross-section between the fixed pulley 15 and the pivotingpulley 13, by appropriate movement of the arc-shaped adjuster 16, slowlyand uniformly.

The first jamming position represents also a safety measure for it getsengaged automatically--that is to say, the user does not have to applyany force on the handle 18. For instance, if the user has fainted awayand is therefore not in the position to handle the jamming device 1,then the latter will wedge the rope 10 automatically in the firstjamming position, thus preventing the user from falling down.

The second jamming position is shown in FIG. 5. In this position actupon the rope 10 three normal forces which are schematically representedby arrows N.

The press-boss 17 is in this case pushed towards the jamming cleat 14;thus the rope 10 gets wedged between the press-boss 17 and the jammingcleat 14. As the pivoting pulley 13 has the form of a droplet whosepoint faces the jamming cleat 14, represents the said point of thepivoting pulley 13 a boss as well. Consequently, the rope 10 is in theform of S three times wedged between the pivoting pulley 13, jammingcleat 14, and the press-boss 17. To prevent, while pressing the handle18, the rope 10 from being jammed between the casing 2 and the handle18, the rope 10 is threaded out of the casing 2 at the side turned awayfrom the handle 18. Thereby acts the carabiner 9 as the guiding agentfor the rope 10.

I claim:
 1. A jamming device for rope and the like, comprising:a. acasing, said casing comprising two parallel flanges; b. a first pivotingpulley (12), a second pivoting pulley (13), a fixed pulley (15), and ajamming cleat (14), the first pivoting pulley (12), the second pivotingpulley (13), and the jamming cleat (15) being mounted between the twoparallel flanges of the casing; c. a lever to which is fastened thefirst pivoting pulley (12), the second pivoting pulley (13), and thejamming cleat (14); d. an arc-shaped adjuster (16), the arc-shapedadjuster (16) being attached to the fixed pulley (15), and being capableof moving the lever (11) away from the fixed pulley (15); and e. apress-boss (17) attached to the arc-shaped adjuster (16); the secondpivoting pulley (13) and the fixed pulley (15) being capable of wedginga rope (10) between the second pivoting pulley (13) and the fixed pulley(15) in a first jamming position; the jamming cleat (14) and thepress-boss (17) being capable of wedging the rope (10) between thejamming cleat (14) and the press-boss (17) in a second jamming position.2. Jamming device according to claim 1, characterized in that the lever(11) is pivoted eccentrically to the geometrical centre of the firstpivoting pulley (12).
 3. Jamming device according to claim 1,characterized in that the jamming cleat (14) is situated between thefirst pivoting pulley (12) and the second pivoting pivoting pulley (13).4. Jamming device according to claim 1, characterized in that thearc-shaped adjuster (16) and the press-boss (17) are equipped with anoperating handle (18).
 5. Jamming device according to claim 4,characterized in that the arc-shaped adjuster (16) is mounted pivotallyin the centre of the fixed pulley (15).
 6. Jamming device according toclaim 1, characterized in that an opening angle (α) of the arc-shapedadjuster (16), owing to a rotation stop (19), can not exceed 60°. 7.Jamming device according to claim 1, characterized in that the secondpivoting pulley (13) has the form of a droplet whose point is orientedtowards the jamming cleat (14), while one of its flanks faces the fixedpulley (15).
 8. Jamming device according to claim 1, characterized inthat the jamming cleat (14) has the form of kidney.
 9. Jamming deviceaccording to claim 7, characterized in that by the help of thepress-boss (17) the rope (10) can be wedged in a form of an S betweenthe jamming cleat (14) and the second pivoting pulley (13).
 10. Jammingdevice according to claim 1, characterized in that the arc-shapedadjuster (16), is furnished with a convex curve by means of which it ispossible to adjust continuously the motion of the lever (11) and thuskeep it under control.
 11. Jamming device according to claim 1,characterized in that either of the flanges (3 and 4) has at an endturned away from the fixed pulley (15) an oblong hole (8) into which acarabiner (9) can be fitted.